Adding Node.js version file support (#338)

action.yml

@@ -7,6 +7,8 @@ inputs:
     default: 'false'
   node-version:
     description: 'Version Spec of the version to use.  Examples: 12.x, 10.15.1, >=10.15.0'
+  node-version-file:
+    description: 'File containing the version Spec of the version to use.  Examples: .nvmrc, .node-version'
   architecture:
     description: 'Target architecture for Node to use. Examples: x86, x64. Will use system architecture by default.'
   check-latest: